• Head of company leaves• Profits are down• Competitor introduces better product• Celebrity stock guru says “sell”• Major political or economic news• Rumors about the company

For example, if earnings beat expectations, investors tend to be more interested in owning the stock than dumping it. Demand exceeds supply, pushing the stock price up.

Even so, it is very hard to predict whether a stock is going to go up or down in reaction to various events. That’s why the stock market is best for investors who are willing to ride out the storms, rather than panic whenever their stocks tumble.